Nope, Still No Such Thing as a Fatal Marijuana Overdose

By all accounts, 31-year-old mother of three Gemma Moss recently smoked half a joint to help her sleep, and then she never woke up: a tragic passing that quickly yielded giddy tabloid headlines touting her as “the first woman in Britain to be poisoned...

And really, the headlines could have gone even further, proclaiming poor Ms. Moss “the first person in recorded history to die of a marijuana overdose!” Which, given the fact that humans have been ingesting the plant in one form or another for more than 10,000 years, certainly sounds like a scoop. Especially when science had previously pegged the dose you'd need to ingest in order to suffer a fatal overdose at considerably higher than half a joint.

According to a 1988 ruling from US Drug Enforcement Agency administrative law judge Francis Young:

Drugs used in medicine are routinely given what is called an LD-50. The LD-50 rating indicates at what dosage fifty percent of test animals receiving a drug will die as a result of drug induced toxicity. A number of researchers have attempted to determine marijuana’s LD-50 rating in test animals, without success. Simply stated, researchers have been unable to give animals enough marijuana to induce death.

At present it is estimated that marijuana’s LD-50 is around 1:20,000 or 1:40,000. In layman terms this means that in order to induce death a marijuana smoker would have to consume 20,000 to 40,000 times as much marijuana as is contained in one marijuana cigarette.... A smoker would theoretically have to consume nearly 1,500 pounds of marijuana within about 15 minutes to induce a lethal response.

So if the rather notably anti-marijuana DEA considers fatally overdosing on chronic nigh well impossible, and if even the world's most rabid drug warriors can't point to a single previous medically confirmed OD, how the heck did we end up with last week's definitive headlines? Is it possible that Gemma Ross rolled up a 3,000-pound joint and then consumed half of it in one sitting?

Well, the British press didn't report on the exact size of her spliff, but it's hard to imagine they make rolling papers that large. No, instead these breathlessly reported stories all relied on the wisdom of one small-town coroner and a local pathologist who share a perhaps less than fully evolved understanding of how marijuana effects the human body.

“The postmortem could find no natural cause for her death"—Sheriff Payne, coroner of Bournemouth, England, wrote in his postmortem—“with the balance of probability that it is more likely than not that she died from the effects of cannabis.”

To which attending pathologist Dr. Kudair Hussein added: "The physical examination and the examination of various organs, including the heart and the liver, showed no abnormality that could account for her death. The level of canabinoids in the blood were 0.1 to 0.15 miligrams per liter; this is considered as moderate to heavy cannabis use. I looked through literature, and it's well known that cannabis is of very low toxicity. But there are reports which say cannabis can be considered as a cause of death because it can induce a cardiac arrest."

So did they list the cause of death as “cardiac arrest?”

No, because as clearly stated, there's absolutely no evidence to demonstrate that.

Did they list the cause of death as “cannabis poisoning,” as widely reported in newspaper stories that quickly went viral?

No, because as they clearly stated, there's absolutely no evidence to demonstrate that. And there's much evidence showing such “poisoning” to be scientifically impossible.

Instead they concluded the cause of death to be “cannabis abuse.” Again, absolutely no evidence to prove this, but since the authorities couldn't come up with anything else to explain a seemingly healthy woman dying in her sleep, why not blame the reefer?

Of course, needless to say, not all of the experts agreed.

“There’s been no history of any verified reports of a death from cannabis ever,” Dr. Alan Shackelford, a Harvard-trained physician and leading medical marijuana advocate in Colorado told theDenver Post. “Cannabis can cause an increased heart rate, and there’s a possibility that it could cause a problem with someone with a pre-existing heart disease—for example, somebody with an elevated heart rate. But there’s no known dose of cannabis that could kill a human... We see unexplained deaths not infrequently. [In this case] the cannabis is a red herring and an incidental finding... I have no idea what caused her death, but I can say with near 100-percent certainty that it wasn’t the cannabis that killed her.”

Meanwhile, David Nutt, former chairman of the British government's Advisory Council on the Misuse of Drugs, doesn't entirely discount the chance that cannabis had some small role in Ms. Moss's untimely expiration, but he says that such a “freak fatality” shouldn't change the way we think about the plant's incredible safety record.

“I cannot begin to understand the pathologist’s certainty that cannabis killed Gemma Moss, but neither do I wish to contradict him outright,” Nutt wrote on the blog of his Independent Scientific Committee on Drugs. “Taking any amount of cannabis, like all drugs, like so many activities, puts some stresses on the body. Cannabis usually makes the heart work a little harder and subtly affects its rate and rhythm. Any minor stress on the body can be the straw that breaks the camel’s back, the butterfly’s wingbeat that triggers the storm. Ms. Moss had suffered with depression, which itself increases the risk of sudden cardiac death. It is quite plausible that the additional small stress caused by that cannabis joint triggered a one-in-a-million cardiac event, just as has been more frequently recorded from sport, sex, saunas and even straining on the toilet.”